The Ames/Salmonella and CHO mammalian cell assays will be used to assess the cytotoxicity and mutagenicity of various heterocyclic amines. The Ames/Salmonella assay will be used to detect the mutagenic activity of food extracts and to guide the purification of new mutagens from flame-cooked beef. The mutation-lowering effects of the flavonoid apigenin and 11 isomers on MeIQx and PhIP will be evaluated using the Ames test. The mutagenicity of PhIP, IQ and MeIQx will be studied in the Ames test using a variety of UDP-glucuronosyltransferase expressing microsomes as the activating system. The Ames test will also be used to screen the mutagenic potency of ten 2-aminoimidazole-azaarene (AIA) compounds and their respective N-hydroxy derivatives. The genetically modified CHO cells will be used to assess the cytotoxicity and mutagenicity of the recently characterized IFP, as well as any additional newly isolated compounds. Cytogenetic end points of SCEs and chromosomal aberrations with IFP and other compounds will also be evaluated using the CHO cells. The core will also assist in evaluating the cytotoxicity and mutagenicity of the cell line expressing UDPglucuronosyltransferase 1A1 gene after it is developed. This CHO mammalian assay is not only a more sensitive system for evaluating the differential cytotoxicity and mutagenicity of compounds, but it is also a better system for understanding the mutagenic mechanism. This core will also be involved in methods monitoring the survival of E.coli K12 in food at different cooking temperatures after various methods of cooking.